Process and apparatus for removing liquids from solid surfaces

ABSTRACT

Method for removing liquid from a non-absorbent article comprising immersing the article into a vigorously agitated solvent bath, transferring displaced liquid and solvent directly to a separation zone, withdrawing liquid which collects as one phase in the separation zone, removing solvent which collects as another phase in the separation zone, recycling this solvent to the solvent bath, and removing the article from the solvent bath. An alternative to the solvent bath is a spray treatment. Apparatus comprises various sumps and piping to accomplish the above, including at least one sump equipped with means for the vigorous agitation of liquid contained therein, such as ultrasonic vibration means if a solvent bath embodiment is employed, or at least one sump equipped with a spraying means if the spray treatment embodiment is employed. The above-described systems are particularly adapted for the removal of water from non-absorbent articles, and particularly articles with relatively inaccessible surfaces.

[s4] PROCESS AND APPARATUS FOR REMOVING LIQUIDS FROM SOLID SURF ACES [75] inventor: Francis John Figiel, Boonton, NJ.

[73] Assignee: Allied Chemical Corporation, New

York, NY.

221 Filed: Feb. 1, 1911 211 Appl. No.: 111,347

Related US. Application Data [63] Continuation-in-part of Ser. No. 805,561, March 10, 1969, Pat. No. 3,559,297, and a continuation-in-part of Ser. No. 831,890, June 10, i969, Pat. No.

ticle comprising immersing the article 1451 Jan. 16, 1973 I 57] ABSTRACT Method for removing liquidfrom a non-absorbent arinto a vigorously agitated solvent bath, transferring displaced liquid and solvent directly to a separation zone, withdrawing liquid which collects as one phase in the separation zone, removing solvent which collects as another phase in the separation zone, recycling this solvent to the solvent bath, and removing the article from the solvent bath. An alternative to the solvent bath is a spray treatment. Apparatus comprises vari- 3,589,023, ous sumps and piping to accomplish the above, including at least one sump equipped with meansfor the [if] "32/9, 34/60 vigorous agitation of liquid contained therein, such as I! .l ultrasonic vibration means a Solvent bath embodi Fle d 0 Search ment is p y or at least one p q pp a spraying means if the spray treatment embodiment is [56] References cued employed. The above-described systems are particu- UNITED STATES PATENTS larly adapted for the removal of water from nonabsorbent articles, and part1cularly articles w1th relative- 3,386,181 6/1968 Steinacker ..34/9 1y inaccessible surfaces. 3,559,297 2/1971 Figiel ..34/9 3,589,023 6/1971 Figiel ..34/9 66 Claims, 10 Drawing Figures 3 i 1 i, I 5 I -l 7 F 75 74 I I A I f I I I .4 T 1 I -1 9 1 i I 4 f r11! I I I I I.

PATENTEDJAH 1a 1975 SHEET 1 [IF 5 IIII I NVEN TOR.

ATTORNEY PATENTEDJAN 16 1973 SHEET 4 OF 5 ATTORNEY.

PATENTEDJM 16 I975 SHEET 5 BF 5 ATTORNEY.

PROCESS AND APPARATUS FOR REMOVING LIQUIDS FROM SOLID SURFACES This application is a continuation-in-part of both of the following described applications:

1. Co-pending, commonly assigned application of Francis John Figiel, entitled Process and Apparatus for Removing Water from Solid Surfaces", Ser. No. 805,561 filed Mar. 10, 1969, now U.S. Pat. No. 3,559,297;

2. Co-pending, commonly assigned application of Francis John Figiel, entitled Process and Apparatus for Removing Water from Solid Surfaces at Low Temperatures", Ser. No. 831,890 filed June 10, 1969, now U.S. Pat. No. 3,589,023.

BACKGROUND OF THE INVENTION There is a need in the art for methods and equipment for separating liquid from liquid contaminated non-absorbent articles. For example, silicon wafers, copper and glass components used in miniaturized electronic circuits need to be dried quickly and thoroughly to avoid the formation of drying stains on the surfaces of such articles. Such stains comprise water-soluble soil material which would adversely affect the electrical properties of these articles. Articles which are heat senstive, such ascertain plastics and metallic parts, cause additional problems in that temperatures used during the drying technique should not adversely affect the articles. A variety of methods and equipment have been devised in order to satisfactorily dry such articles and all suffer from one or more serious disadvantages.

Thus, methods which are based on the use of air for evaporative drying are disadvantageous because high temperatures are employed and because the use of air in certain circumstances permits the formation of oxide films on the articles which adversely affects electrical properties. Solvent drying techniques and apparatus which are known in the art suffer from various disadvantages such as use of flammable solvents, contamination of the dried articles with an additional material such as a detergent which has to be removed, failure to provide a continuous mode of operation, and complication of equipment and equipment parts resulting in increased capital costs and operating expenses.

It is accordingly an object of this inventionto provide methods and apparatus capable of effectively and quickly removing liquids from non-absorbent articles, which methods and apparatus do not suffer from the disadvantages possessed by previously known methods and apparatus used for this purpose.

A specific object of this invention is to provide a novel method and apparatus for drying water-contaminated non-absorbent articles, which apparatus is simple in construction and operation and which there fore requires low capital costs and operating expenses.

Another specific object of the invention is to provide a novel process and apparatus for quickly and efficiently removing water from the surfaces of heat sensitive articles at temperatures below about 80F.

Another object of the invention is to remove liquids, particularly water, from a plurality of articles having surfaces in contact with one another, or from single articles having relatively inaccessible surfaces.

Other objectsand advantages of the invention will be apparent from the following description.

SUMMARY OF THE INIVENTION It has been discovered that the :above objectives can be accomplished by the following method and apparatus.

. The method comprises essentially immersing an'article containing a liquid contaminated surface into a solvent bath having a different density than the liquid and vent to separate into two phases therein; withdrawing from the system liquid which collects as one phase in the separation zone; removing from the separation zone solvent which collects as another phase in the separation zone; recycling the solvent removed from the separation zone to the solvent. bath; and removing the article from the solvent bath.

The apparatus of the invention which is adapted to carry out the above-described method comprises essentially the following in combination: a first sump adapted to contain a liquid; means to vigorously agitate liquid contained within the first sump and to produce turbulence throughout said liquid; a second sump adapted to contain a liquid; means for transferring liquid which overflows from the first sump to the second sump; means for removing liquid which collects as an upper phase from the upper portion of the second sump; means for removing liquid which collects as a lower phase from the lower portion of the second sump; and means for transferring liquid removed either from the lower portion of the second sump or from the upper portion of the second sump to the first sump.

In another embodiment of the method of the invention, the method comprises essentially spraying an article containing a liquid contaminated surface with a solvent having a different density than the liquid and in which the liquid is between about 0.001-5 percent by weight soluble, thereby displacing liquid from the 'article; collecting the displaced liquid and solvent; permitting the displaced liquid and the solvent to separate into two phases; causing the upper phase with accompanying amounts of the lower phase to overflow into a separation zone and permitting the liquid and the solvent to separate into two phases therein; withdrawing from the system liquid which collects as one phase in the separation zone; removing from the separation zone solvent which collects as another phase in the separation zone; recycling the solvent removed from the separation zone to the solvent bath; and removing the article from the spray.

The apparatus according to the invention which is adapted for carrying out the above-described spray treatment embodiment of the invention comprises essentially means to spray articles with liquid; a first sump adapted to receive liquid which is discharged from the spray means; a second sump adapted to contain a liquid; means for transferring liquid which overflows from the first sump to the secondsump; means for removing liquid which collects as an upper phase from the upper portion of the second sump; means for removing liquid which collects as a lower phase from the lower portion of the second sump; and means for transferring liquid removed either from the lower portion of the second sump or from the upper portion of the second sump to the first sump.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view in partial section of one embodiment of the invention showing the component parts integrally contained in an open-top treatment vessel, including a main sump equipped with an ultrasonic transducer for the purpose of introducing ultrasonic vibration to liquid contained in that sump.

FIG. 2 is a front view in partial section of the embodiment of FIG. I, viewed through the cutting plane of line 22 of FIG. 1.

FIG. 3 is a plan view in partial section of another embodiment of the invention showing the component parts integrally contained in an open-top treatment vessel, including a means for agitating or vibrating a plurality of articles within the main sump.

FIG. 4 is a front view in partial section of the embodiment of FIG. 3, viewed through the cutting plane of line 44 of FIG. 3.

FIG. 5 is a plan view in partial section of another embodiment of the invention, showing the component parts integrally contained in an open-top treatment vessel, similar to the embodiment of FIG. 1, except that an additional sump is provided, which additional sump is free of means to create turbulence in liquid contained 88 ofFIG.7.

FIG. 9 is a plan view in partial section of another embodiment of the invention, showing the component parts integrally contained in an open-top treatment vessel, including a boiling sump and a main sump equipped with an ultrasonic transducer for introducing ultrasonic vibration to liquid contained within the main sump.

FIG. 10 is a front view in partial section of the embodiment of FIG. 9, viewed through the cutting plane of line 10-10 of FIG. 9, additionally showing a drier, reservoir, pump and associated circuits.

DETAILED DESCRIPTION OF THE INVENTION AND OF THE PREFERRED EMBODIMENTS Solid surfaces which can be treated in accordance with the invention may be constructed of a wide variety of non-absorbent solid materials. Illustrative materials of construction include a variety of metallic materials such as ferrous metals, copper, nickel, chromium, stainless steel, aluminum and alloys thereof. Examples of non-metallic materials are glass and plastics, such as' polytetrafluoroethylene, polychlorotrifluoroethylene, polyethylene and nylon. The articles may be formed as machined parts such as silicon wafers, copper printed boards and the like, or may be formed as unmachined parts such as aluminum corrugation and strip stock.

The shape of the article is not critical, for the method and apparatus of the invention are effective in removing even small traces of liquid from small cracks and crevices as well as from large surfaces. In fact the present invention is particularly suited for removing traces of liquid from articles having unusual configurations or configurations which for some other reason present relatively inaccessible surfaces.

The choice of solvent which is used in the method of the invention is important. The solvent should be one which is inert to the article being treated, or at least which is not undesirably reactive with the article. The solvent should also be one in which the liquid being removed is between about 0.00l5 percent by weight soluble. Any solvent which meets these characteristics is operable in the subject process. Preferably, but not necessarily, the solvent is denser than the liquid to be treated. Approximately a 0.001 percent by weight, and

preferably 0.01 percent by weight, minimum solubility of liquid in the solvent is desirable to assist the solvent to penetrate the liquid film and readily displace the liquid. Preferably, when the liquid to be removed is water, the solvent should be one in which water is at least 0.1 percent by weight soluble and, still preferably, one in which water 'is at least 0.5 percent by weight soluble. If the liquid is more than about 0.5 percent by weight soluble in the solvent, sufficiently efficient separation of the liquid from the solvent is not possible according to the invention method. The ideal solvent for the novel process is one which possesses all of the following characteristics: maintains its original composition, temporarily decreases the overall surface free energy in order to break up liquid films and wet the substrate, effectively washes liquid from the wetted objects, is essentially immiscible with the liquid, and evaporates without leaving a stain. A number of single substances may be used alone in the novel method. A preferred class is selected from halogenated hydrocarbons boiling between about 0100C. and having a density greater than about 1.3 gm/cm. at 20C. Depending on the particular application, the following are illustrative of such single substances which may be employed: 1,l,2-trichloro-1,2,2-trifluoroethane and tetrachlorodifluoroethane (tetrachlorodifluoroethane may be used alone as the symor unsym-isomer. It is sold commercially, however, as a mixture of these two isomers and may be used as a solvent in the method described herein in this form. The isomeric mixture behaves like a single substance and will be so regarded herein), trichloromonofluoromethane, isomers and isomeric mixture of trichlorobenzene, methylene chloride, carbon tetrachloride, carbon tetrabromide, chloroform, bromoform perchloroethylene, trichloroethylene, and the like. These single substances are particularly useful in the spray treatment embodiment of the invention when used to treat articles contaminated with aqueous solutions of one kind or another. For particular applications, there may be no single substance known which is outstanding for the purpose; however, solvents which perform better than the known single substances may be tailored .by mixing two or more single solvent materials.

In those embodiments in which water is the liquid contaminant to be treated, the preferred solvents are mixtures in which the mixtures contain at least one substantially water-immiscible halogenated hydrocarbon component boiling between about 0-l0 0C. and having a density greater than about 1.3 gm./cm. at C. and at least one non-halogenated organic liquid miscible with the halogenated hydrocarbon component and with water, which boils between about 0l50C. and has a density less than about 1.0 gm./cm.- at 20C. Surprisingly, it has been found that the presence of water as an azeotrope with one or more of the mixture components does not adversely affect the invention method. A particularly effective group of solvents within this class are two-component solvents in which the water-immiscible and water-miscible components are as described above and in whichthe water-immiscible componentconstitutes between about 80-995 wt. of the mixture. The preferred water-immiscible component is a member of the group consisting of 1,1,2- trichlorol ,2,2-trifluoroethane and tetrachlorodifluoroethane. The preferred water-miscible component is selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, acetonitrile, acetone, nitromethane and dioxane. The preferred solvent within this class is a mixture of 1,1,2- trichloro-l ,2,2-trifluoroethane and isopropanol. The weight percent of l,l,2-trichloro-l ,2,2-trifluoroethane should be in the range of about 85-98 percent, still preferably from 90-98 percent, and most preferably about 97 percent. The 97 weight percent mixture is most preferred because it is a constant boiling azeotropic mixture which maintains its composition during use. This is particularly important in those embodiments of the invention wherein a solvent mixture is heated to boiling to generate vapors. When nonazeotropic mixtures are employed, the mixtures fractionate upon boiling in the boiling sump, eventually requiring composition adjustment. in the light of the above discussion, one of ordinary skill in the art can readily devise suitable solvent mixtures for specific applications by routine testing and evaluation for the desired properties.

The liquid to be removed from the article may be organic or inorganic in nature and may comprise organic or inorganic solutions which may additionally contain a variety of dissolved or suspended materials. Water is the most common and typical liquid which is desirable to remove from solid surfaces in accordance with the invention method and apparatus. Aqueous solutions such as dilute acid solutions of HCl, H 80, and HNO and also alkaline solutions, are additional examples of liquids which may be removed in accordance with the invention. These solutions may contain dissolved materials such as oxides, for example, silicon oxide, or salts of Zn, Cu, Ni, Cd, Au, Ag, Cr, Pb and Sn, for example. Metal cyanides, sulfates and fluoborates are examples of such salts. The removal of such solutions is useful in the manufacture of silicon single crystals, wherein silicon oxide coatings may be removed with acid solutions, such as HCI solutions, and also in the removal of photoresist stripping solutions from wafers having an aluminum coating, wherein the solvent may be organic in nature. Other examples of industrial solutions which may be treated in accordance with the invention are the various metal plating solutions, including the various precious metal plating solutions. A major source of pollution lies in the disposal of rinse waters from such metal plating operations, which contain substantial quantities of acidic plating solutions and metal contaminants.

in some applications, a surfactant should be incorporated in the salt to assist in the displacement of the water, the aqueous solution, or other liquid from the surfaces of the articles. The nature of suitable surfactants is well known to those skilled in the art. The surfactant should be substantially insoluble in water and preferentially more soluble in the solvent. Examples of suitable surfactants include long-chain alkyl trimethyl ammonium halides, such as cetyl trimethyl ammonium bromide, long-chain alkyl pyridinium chlorides and bromides, long-chain alkyl dimethyl benzyl ammonium chlorides and alkyl phosphate esters neutralized with saturated aliphatic amides. The optimum amount of the surfactant to beused will vary from about 0.00l to 10 percent by weight of the solvent solution, depending on the particular application involved. A more detailed description of suitable surfactants and their method of use in this art may be found in U. S. Pat. No. 3,386,181.

For purpose of illustration, the invention will hereinafter be more particularly described with respect to the removal of water from non-absorbent surfaces, although as clearly indicated herein, the invention is not intended to be so limited.

The novel process and apparatus of the invention may be more readily understood by reference to the drawings which illustrate preferred embodiments and the best modes presently contemplated for practicing the invention.

Although all the apparatus components need not'be assembled in a single container, for convenience, as shown in FIGS. 1 and 2,'for example, the components are all assembled in an open top treatment vessel 1. -With further reference to FIGS. 1 and 2, a rectangular dewatering sump 2, cooled by coolant jacket 3, is positioned adjacent a rectangular water separating sump 4 so that liquid contained in the dewatering sump can overflow over wall 5 of dewatering sump 2 into the water separating sump 4. The direct overflow feature from dewatering sump 2 into water separating sump 4 is preferred but should not be construed as being limiting of the invention. The liquid could be transferred to sump 4 from sump 2 via an intermediate tank such as a reservoir or auxilliary settling tank. The water separating sump is shown in the drawing as having a smaller surface area than the dewatering sump. Water separating sump 4 is equipped with an overflow pipe 6 which protrudes from the upper portion of the water separating sump and extends outwardly through the wall of treatment vessel 1 and coolant jacket 3, permitting the continuous removal of water which rises to the surface of the solvent and water mixture which collects in water separating sump 4. lf a solvent is employed which is less dense than water, then, of course, the solvent would rise to the surface of the water and be removable through overflow pipe 6. Coolant jacket 3 extends around water separating sump 4. Coolant jacket 3 is not essential to the operation of the apparatus for all applications but is necessary if it is desired to conduct the drying operation below room temperature. it may be desirable to provide heating means for the dewatering sump in a particular application. A drain pipe 7 in the lower portion of water separating sump 4 extends outwardly through the wall 8 of the water separating sump and runs upwardly and parallel to wall 8 before turning to empty into reservoir 9, permitting the continuous transfer of solvent collected towards the bottom of water separating sump 4 to reservoir 9. The height of drain pipe 7 determines the level of solvent in water separating sump 4. Overflow pipe 6 is connected to the water separating sump at a point slightly above the level of drain pipe 7.

It is preferable, for reasons of efficiency, but not absolutely necessary, that the surface area of water separating sump 4 be smaller than the surface area of dewatering sump 2. Preferably, the ratio of the area of the opening of the water separating sump 4 to the area of the opening of the dewatering sump 2 should be between about 1:5 and 1:100 and, still preferably, between about 1:10 and 1:20.

Solvent removed from the water separating sump 4 through drain pipe 7 is optionally conveyed through drier 10 and from there is fed to reservoir 9 through pipe 11. Pump 12 then feeds the solvent through pipe 13 into dewatering sump 2. Optionally, as best shown in FIG. 1, pipe 13 terminates with a perforated section 14 which is parallel to side wall 15 of dewatering sump 2 and extends for a substantial portion of the length of side wall 15. Perforated section 14 of pipe 13 terminates on a level with the top of dewatering sump 2 so that the solvent fed through this member helps push any water layer rising to the top of the solvent liquid in dewatering sump 2 over wall 5 into water separating sump 4. This would normally only take place if the ultrasonic vibration is stopped after immersing the article and the water and solvent layers are permitted to separate. When the ultrasonic vibration is maintained and the drying procedure is operated continuously, an ultrasonically agitated mixture of the solvent and water overflows from sump 2. This mixture may be dumped directly into water separating sump 4 or it may first be transferred to a settling tank, or other means to separate gross quantities of solvent from water, and then to water separating sump 4. Optionally, but preferably, a trough 16 is provided around the perime- 'ter of the treatment vessel above dewatering sump 2 to collect condensed water vapor which may collect on the walls of the treatment vessel due to environmental conditions. Obviously, condensation of water on the walls of the treatment vessel will be more pronounced when the system is operated with cooling. Condensed water may be removed from the trough by means of a drain pipe, such as 17. The shapes and configurations of water separating sump 4 and dewatering sump 2 are not critical. In another embodiment, for example, not shown in the drawings, water separating sump 4 is essentially U shaped and the dewatering sump 2 is rectangular in shape and is positioned within the U of the water separating sump so that overflow of liquid from the dewatering sump into the water separating sump can take place over three walls of the dewatering sump.

Ultrasonic transducer 18 is provided in the bottom of dewatering sump 2 for the purpose of vigorously agitating and producing turbulence throughout the liquid contained in this sump. Any other means to produce vigorous agitation and turbulence throughout liquid contained in this sump may be employed. By turbulence throughout the liquid, it is intended to cover only those means capable of producing turbulence in liquid contained in all areas or zones of the sump, as contrasted with, for example, those means which are capable only of producing turbulence in liquid contained in one area or zone of the sump, while maintaining, relatively one or more areas or zones of quiescence elsewhere within the sump. It is intended to include within the scope of this invention, those means which initially produce turbulence in only one area or zone of the sump, but which by convection, shortly produce turbulence throughout the sump.

ln operation of the embodiment shown in FIGS. 1

and 2, a suitable solvent liquid is charged to completely fill dewatering sump 2 and partially fill reservoir 9. Cooling agent, for example water, at the desired temperature, is circulated through coolant jacket 3 if the drying operation is to be conducted below room temperature. The temperature at which the drying operation is conducted may vary according to particular needs. For the present purposes, the temperature may vary from 0C. to and including the boiling point of the solvent. Preferably, room temperature or below is employed. Ultrasonic vibration is commenced. The intensity of the ultrasonic vibration employed should be sufficient to effect vigorous agitation of the solvent in the sump and produce turbulence throughout the solvent bath in the sump. Such can be determined by routine experimentation. Generally, an operating frequency between about 15 and kilocycles per second should be employed. The preferred frequency range is from about 15 to about 40 kilocycles per second. The generator output is dependent on the size of the container. For example, a six gallon tank would require about 500 watts to maintain a uniform field of ultrasonic vibration. Again, this can be determined by routine experimentation, depending on individual requirements. The article to be treated is immersed into the ultrasonically agitated solvent liquid bath of dewatering sump 2. The solvent displaces the water from the article. The volume of the article immersed in dewatering sump 2, as well as the volume of water displaced, causes ultrasonically agitated mixture of solvent and water to overflow from dewatering sump 2 over wall 5 into water separating sump 4. If desired the ultrasonic vibration may be stopped after the desired immersion time and the solvent and water permitted to settle into two phases, the water phase rising to the top. In this way lower volume throughputs are required through water separating sump 4 and the operation of water separation in sump 4 is not .inhibited by the discharge into this sump of ultrasonically agitated liquid. Of course, if the ultrasonic vibration is stopped, the operation becomes semicontinuous rather than continuous. Another mode of operating continuously is by transferring the agitated mixture of water and solvent to a separate reservoir and settling tank to effectuate bulk separation, as described above, followed by final treatment of the remaining solvent and water mixture in water separating sump 4. The solvent and water which collect in water separating sump 4 separate into two layers, the heavier solvent layer on the bottom. The upper water layer is continuously withdrawn through overflow pipe 6. The lower solvent layer is withdrawn through drain pipe 7 and passes through drier l0 and from there via pipe 11 into reservoir 9. From reservoir 9 the solvent liquid is pumped by eamns of pump 12 through pipe 13 into dewatering sump 2. The cycle rate of solvent into dewatering sump 2 is regulated so as to maintain the level of solvent in dewatering sump 2 at the top of the sump. No substantial amount of solvent is lost from the system except incidentally as vapor loss.

I that is required. Preferably, the dip time is between about -30 seconds.

When the article is withdrawn from the solvent liquid bath in the dewatering sump, it may be exposed to the atmospheric environment until any traces of solvent film evaporate, or it may be subjected to additional treatments, as will be described in more detail herein,

vent, thereby resulting in incomplete drying. Illustrative of such difficult to dry surfaces are the mutual contact points of small parts when dried in bulk such as the adjacent, flat surfaces of razor blades and the contact points of closed switches. In these cases, the nature of the agitation must be sufficient to produce a sufficient degree of turbulence throughout the bath to cause the contacting surfaces to separate. from one another.

Ultrasonic vibration in the manner described previously is an effective means of accomplishing this degree of turbulence.

Another means for readily accomplishing a sufficient degree of turbulence for this purpose is by vigorously agitating the articles to be treated in the solvent solution. By agitating the articles, it is intended to also include agitating a carrier or holder for the articles. It has proven difficult to provide a sufficient degree of turbulence in the solvent bath by agitating the bath other than by ultrasonic vibration, although this is possible.

When the turbulence is created by agitating the articles, it 'has been found that an up-and-down motion with strokes of short duration, for example in the order of 0. 1-] second, is most effective.

FIGS. 3 and 4 illustrate this embodiment of the invention. The embodiment of FIGS. 3 and 4 is identical to the embodiment described in FIGS. 1 and 2, excepting that a vibrating carrier is shown as the means for creating turbulence in dewatering sump 2, rather than ultrasonic vibration. To facilitate comparison and 1 basket. For purpose of illustration, the articles are.

shown separated from one another, but it is to be understood, as indicated above, that in the most advantageous application of the embodiment of FIGS. 3 and 4, the articles contact each other, but are free to move about responsive to the turbulence created in the solvent bath within which they are dipped.

Vibrator 22 imparts a short, quick up-and-down movement to holders l9 and 20. Cable 23 serves to permit suspension and removal of the vibrating holders l9 and 20 with attached articles 21 from the solvent bath in dewatering sump 2.

As explained above in connection with the embodiment of FIGS. 1 and 2, the agitated solvent treatment of this embodiment could be preceded or followed by any combination of additional treatments, particularly the ones described herein such as dipping in a nonagitated bath, a solvent vapor rinse, a spray rinse, or dipping in another agitated bath such as an ultrasonically agitated bath.

FIGS. 5 and 6 illustrate a preferred embodiment which provides for dipping of the articles to be treated in both an agitated bath and a non-agitated bath. The components visible in FIG. 6 are identical to the embodiment shown in FIG. 2, with the following exceptions. The ultrasonic transducer is not connected to sump 2 as shown in FIG. 2, but is connected to new sump 24 located directly behind sump 2. For ease of comparison and description, the components which are identical in the embodiments of FIG. 2 and FIGS. 5 and 6 bear the same numbers. Their function and operation need not be described again.

Ultrasonic sump 24 and corresponding water separating sump 25 contain identical parts and plumbing. The parts associated with sumps 24 and 25 are shown with the same numbers corresponding to the equivalent parts in sumps 2 and 4, except that the prime symbol is employed as a superscript.

Dewatering sump 2 is adapted to contain liquid in a substantially quiescent state. It is free of agitation means or baffles which would create turbulence in the liquid contained therein. If it is desired to operate this sump at temperatures above room temperature upto the boiling point of the solvent, a heater can be situated in the sump for this purpose. In a preferred embodiment, however, the dewatering sump is adapted to contain aliquid at a temperature below its boiling point or below room temperature, and may include cooling means. A coolant jacket 3 is shown in the drawings. The operation of non-agitated sump 2 is completely independent of the operation of ultrasonicallyagitated sump 24. The operation of the ultrasonically agitated tank has been described in the description of the embodiments of FIGS. 1 and 2. The non-agitated sump 2 is charged with the chosen solvent liquid and the article to be treated is immersed into the solvent bath. In this sump, water which is displaced from the article by the solvent floats to the surface of the heavier, substantially water-immiscible solvent, first as small droplets and later as a thin continuous layer as greater quantities of water are displaced. The volume of the article immersed in dewatering sump 2, as well as the volume of water displaced, causes liquid to overflor from dewatering sump 2 over wall 5 into water separating sump 4. This liquid comprises essentially the water layer formed on top of the heavier solvent layer in dewatering sump 2, together with quantities of displaced solvent. This overflow is assisted by the action of distributor pipe 14 which spreads the solvent feed over a wide area at the level of the surface of the liquid in sump 2 and in a direction towards overflow wall 5. The solvent and water which collect in water separating sump 4 then separate into two layers, which layers are handled as described previously. The length of time of immersion of the article in the liquid bath of the non-agitated dewatering sump is no more critical than the immersion time in the liquid bath of the agitated sump. Again, a dip time of between about l-30 seconds is generally all that is required, with a preferred dip time of btweeen about 20-30 seconds. With this sump, a gentle swirling type action may be imparted to the bath, if desired, in order to aid in the displacement of the water. It is not desired to significantly agitate the bath in this sump, however, since this would promote increased solubility of the water in the solvent and complicate subsequent water separation. It is important to maintain in a substantially quiescent state the solvent liquid bath in this non-agitated dewatering sump.

With respect to the embodiment of FIGS. 5 and 6, the article to be treated may be immersed first in the non-agitated sump 2 and then in the agitated sump 24, or vice-versa. Preferably, gross amounts of water are removed first in the non-agitated sump, followed by removal of residual traces of moisture, if any, in the agitated sump. Obviously, this embodiment can be modified in a number of ways without departing from the spirit of the invention. For example, a single solvent feed and recycling mechanism could be adapted for use for both of the non-agitated and the agitated sumps. Additionally, a single water separating sump could be employed, with liquid from both of the non-agitated and the agitated sumps overflowing directly into a common water separating sump. Other such variations will readily occur to persons skilled in the art.

As was indicated in the case of the other embodiments discussed herein, additional treatment steps may be incorporated either before, after or between the non-agitated bath and agitated bath treatments described above. Illustrative of such treatments are vapor rinsings and spray treatments.

FIGS. 7 and 8 show another preferred embodiment of the invention characterized by the provision of means to spray treat the article, collect the displaced liquid from the article and solvent, and then separate the displaced liquid and solvent substantially as described heretofore. 'The components and arrangement in this embodiment are substantially the same as shown in the embodiment of FIGS. 1 and 2 with the following exceptions: I spray head 26 is provided in the wall in proximity to the top of sump 2; (2) in the embodiment of FIGS. 7 and 8, there is no distributor pipe member 14 to dispense liquid across the surface of the bath contained in sump 2; and (3) there is no sonic transducer member 18 provided on the bottom of sump 2. To facilitate illustration and description, those parts in the embodiment of FIGS. 7 and 8 which have identical counterparts in the embodiment of FIGS. 1 and 2, have been assigned the same numbers.

In operation of this embodiment, the article to be treated is lowered within the chamber 1 in a position adjacent spray head 26 but over sump 2, so that displaced water and discharged solvent may be collected in sump 2. Eventually sump 2 will fill up'completely with a mixture of displaced water and solvent. Since this sump is not provided with agitating means, the water and solvent will tend to form two separate layers with the heavier solvent layer on the bottom as described in the case of the non-agitated sump member of the embodiment of FIGS. 5 and 6. The layer of water rising to the top of sump 2, together with accompanying amounts of solvent, overflows wall 5 into water separating sump 4 wherein the water and solvent are permitted to form separate layers. As described in connection with the previous embodiments, water may then be removed from the system. The separated solvent is recycled for use through the same type of recycling system as described heretofore, but is returned as feed to spray head 26 instead of as feed to the surface of the solvent liquid bath as was the case in the previously described embodiments. Preferably, spray head 26 is located on the outside wall of treatment vessel 1 so that the spray is directed across the surface of the solvent bath in sump 2 towards the overflow wall to water separating sump 4. In the way, the solvent spray can be used for the dual purpose of rinsing the article and for sweeping the water layer rising to the top of the bath in sump 2 over wall 5 into water separating sump 4.

Optionally, the article may be dipped into the solvent bath formed in sump 2 before or after the spray treatment. If desired, sump 2 can be charged with solvent before startup, so that a solvent rinse may be employed before the spray treatment. As in the case with the other embodiments described above, the abovedescribed treatment may be preceded or superceded by any one or a combination of other treatment steps such as vapor rinses and dips in agitated baths.

FIGS. 9 and 10 illustrate another embodiment of the invention incorporating an ultrasonically agitated solvent bath and means for effectuating a vapor rinse of the treated articles. The components are shown assembled in an open-top treatment vessel 27. Rectangular dewatering sump 28, optionally cooled by water jacket 29, is positioned adjacent a rectangular water separating sump 30 so that liquid contained in the dewatering sump can overflow over wall 31 of dewatering sump 28 into the water separating sump 30. Ultrasonic transducer 32 is affixed to the bottom of dewatering sump 28 for the ultrasonic agitation of liquid contained within dewatering sump 28. The water separating sump preferably has a smaller surface area than the dewatering sump. Water separating sump 30 is equipped with an overflow pipe 33 which protrudes from the upper portion of the water separating sump and extends outwardly through the wall of water treatment vessel 27 'and cooling jacket 29, permitting the continuous preferably contains a larger surface area than water separating sump 30. The height of drain pipe 34 determines the level of solvent in water separating sump 30. Overflow pipe 33 is connected to the water separating sump at a point slightly below the level of drain pipe 34.

Heating means 37 is provided at the bottom of boiling separating sump 30 is preferably smaller than the sur- 1 face area of either dewatering sump 28 or boiling sump 36. Still preferably, the ratio of the area of the opening of the water separating sump to the area of the opening of the dewatering sump or to'the area of the opening of the boiling sump, should be between about 1:5 and 1:100, and even more preferably, between about 1:10 and 1:20.

The upper portion of treatment vessel 27 is equipped with a cooling jacket 39 to condense solvent vapors generated from the boiling sump. A trough 40 is provided around the perimeter of the treatment vessel below the cooling jacket to collect condensate running down the walls of the treatment vessel. The condensate is cycled to the dewatering sump. This cycling may be essentially direct, flowing only through miscellaneous auxilliary components such as driers, reservoirs, and

' the like, or, it can be indirect by first flowing into water separating sump 30, which, of course, completes the cycle .by feeding dewatering sump 28. In the embodiment of FIGS. 9 and 10, pipe 41, controlled by valve 42, optionally conveys the solvent condensate through a drier 43 and fromthere solvent condensate is fed to a reservoir 44 through pipe 45, controlled by valve 46. Pump. 47 then feeds the solvent through pipe 48 directly into dewatering sump 28. The solvent vapor condensate may first be transferred to water separating sump 30, however, and the cycle to dewatering sump 28 completed subsequently. in this way, the solvent bath in dewatering sump 28 may be kept very dry, if it is necessary or desirable to be so in the particular operation being carried out, without the need to circulate the condensate which has small amounts of entrained water, through an auxilliary drier. A drier could still be employed, of course, if desired. Preferably, as shown in FIG. 10, pipe 48 terminates on a level with the top of dewatering sump 38 so that the solvent fed through pipe 48 helps push any water layer rising to the top of the solvent liquid in dewatering sump 28 over wall 31 into water separating sump 30. As noted previously, in an ultrasonically agitated sump, a separate water layer will collect at the top only if the ultrasonic agitation is stopped long enough for the water and solvent layers to phase separate. Pipe 48 may terminate with a treatment vessel 1 in order to more effectively contact any such water layer formed with the cycled solvent liquid stream.

In operation, a suitable solvent liquid is charged to partially fill the boiling sump 36 and to completely fill dewatering sump 28. The quantity of solvent charged to boiling sump 36 is not critical as long as sufiicient solvent is maintained therein in the liquid phase to provide a continuous source of solvent vapor when boiled.

The solvent in sump 36 is heated to boiling by means of v heater 37. Solvent vapors are generated and rise to permeate vapor space 49. Cooling; water is circulated through cooling jackets 29 and 39. The temperature of the water coolant in cooling jacket 29 is maintained at about ambient temperatures. This controls the temperature of the liquid in dewatering sump 28 and water separating sump 30 to at least about 10C. above the dew point of the environment. Under such conditions, the tendency for moisture in the air to become ab-' sorbed is minimized. The temperature of the water coolant in cooling jacket 39 is controlled so as to create a good condensation surface on the upper portion of the inner walls of the treatment vessel.

Ultrasonic vibration is commenced. The article to be treated is immersed into the ultrasonically agitated solvent liquid bath in dewatering sump 28. The solvent and the agitating action displaces the water from the article and a mixture of ultrasonically agitated waterand solvent overflows over wall 31 into water separating sump 30. Tl-le solvent and water which collect in water separating sump 30 separate into two layers, the heavier solvent layer on the bottom. The upper water layer is continuously withdrawn through overflow pipe 33. The lower solvent layer is withdrawn through drain pipe 34 and overflows into boiling sump 36. The solvent in boil- I ing sump 36 is substantially water-free. The substantially water-free solvent vapors generated in boiling sump 36 rise into vapor space 49 and condense on the upper portion of the insidewalls of the treatment vessel in the vicinity of cooling jacket 39. The condensed solvent vapors 50 run down the walls of the treatment ves sel into trough 40 from where they eventually cycle to dewatering sump 28 as shown in the drawing, through the recycling equipment 41, 42, 43, 44, 45, 46, 47 and 48 discussed above or, as discussed above, if desired, to water separating sump 30. Tile cycle' rate of solvent into dewatering. sump 28 is regulated so as to maintain the level of solvent in dewateringsump 28 at the top of the sump. No substantial amount of solvent is lost from the system, except incidentally as. vapor loss. Solvent make-up can be added to solvent feed cycle pipe 48 as necessary.

The length of time of immersion of the articlein the ultrasonically agitated liquid bath of dewatering sump 28 is not critical. Generally, between about lO-30 seconds dip time is all that is required. Preferably, the dip time is between about 20-30 seconds.

When the article is withdrawn from the solvent liquid bath in the dewatering sump, it is suspended in vapor space 49 and exposed to the solvent vapors generated by the boiling solvent liquid bath in boiling sump 36 to flash off minute traces of moisture that may still be present on the article. Generally, about 5-30 seconds are all that are required for this purpose. However, a vapor hold time of about 5-20 seconds is preferred. As in the case with the other embodiments described heretofore, the treatment steps described above may be preceded or superceded by other treatment steps as described herein, as desired. For example, such other treatment steps may include singly, or in combination, spray treatments and dips in non-agitated solvent baths.

The following examples illustrate practice 7 of preferred embodiments of the invention to dry a plurality. of articles having surfaces in contact with one another. As explained herein, such articles are particularly difficult to dry thoroughly with existing equipment.

EXAMPLE 1 The apparatus employed is substantially as shown in FIGS. 9 and of the drawings. The capacities of the watering sump 28 and reservoir 44 are 1 gallon each. The ratio of the surface area of the watering separating sump 30 to the surface area of the dewatering sump 28 is 1:10. The 1 gallon dewatering sump is completely filled with a solvent comprising the azeotrope of about 97 weight percent of l,l,2 trichloro-l,2,2- trifluoroethane and about 3 weight percent isopropanol. Reservoir 44 is charged with one-half gallon of the indicated solvent. The drying operation is conducted at room temperature. Accordingly, no cooling agent is circulated through cooling jacket 29. The solvent liquid in boiling sump 36 is heated to boiling to generate solvent vapors in vapor space 49. A stainless steel wire basket, 5 inches by 4 inches and 1.25 inches deep, is filled with copper tabs 0.025 inches in diameter, 0.020 inches in thickness. The basket contains approximately 300 tabs. The total weight of the copper tabs is 30.5580 grams and the weight of the basket is 60.2730 grams. The basket containing the tabs is wetted with water to a pick-up of 5.5 grams water. The basket containing the copper tabs is dipped in the solvent in sump 28 for seconds and then is held in the vapor space above boiling sump 36 for a vapor rinse with boiling solvent vapors for 1 minute. The basket containing the copper tabs is removed from the treatment vessel and is weighed to determine the water loss. It is determined that 98.1 percent of the water which wetted the copper tab parts is removed.

The above experiment is repeated except that, in accordance with the invention, before immersing the basket containing the copper tabs in the solvent bath contained in dewatering sump 28, a sonic input of kilocycles per second, using a generator output of 250 watts, is made to the solvent bath by means of the ultrasonic transducer 32. After the vapor rinse treatment and weighing, it is determined that 100.0 percent of the water is removed.

EXAMPLE 2 The apparatus employed is substantially the same as shown in F168. 3 and 4 except as follows: A solvent spray means is affixed to the wall of the treatment vessel above sump 2, as illustrated by FIG. 8; a boiling sump is included within the system as shown in FIG. 10.

The capacities of the sumps and the relative dimensions of the sumps are as described in Example 1. The solvent employed is the azeotrope of about 97 weight percent of 1,1,2-trichloro-1,2,2-trifluoroethane and about 3 weight percent isopropanol. The articles are wet perforated molybdenum wafers 3 inches in diameter and about 0.005 inches in thickness. The wafers are suspended from holders l9 and 20 every one-eighth inch.

The wafers are treated by the following series of steps in the order indicated:

1. A vapor rinse above the boiling sump for 15 seconds;

4. A second vapor rinse for 120 seconds.

Upon removal from the system, upon visual inspection, the articles are seen to have wet spots, particularly in the areas of contact with holders 19 and 20. The articles also exhibit water spots on their surfaces.

The above experiment is repeated except that upon dipping into the solvent bath, the holder is vibrated in an up-and-down motion by inducing about a 3 inch stroke every one-fifth second. Upon removal from the system, visual inspection shows the articles to be perfectly dry, even in the contact areas, and free from water spots.

EXAMPLE 3 The apparatus employed corresponds to the embodiment illustrated in FIGS. 7 and 8. The capacities and relative surface areas of the sumps are as described in Example 1. The articles treated are small clustered polyethylene parts which have been etched in a bath containing a mixture of sulfuric acid, phosphoric acid and chromic acid. The etched parts contain residual amounts of the acidic etching solution, which it is desired to remove. The solvent employed is pure 1,1,2- trichloro-l,2,2-trifluoroethane. The articles are suspended in clusters adjacent the spray head 26 and are subjected to the action of the solvent spray for about 15 seconds. Weighing the parts before and after treatment shows that 98 percent of the acidic etching 2. A dip (without vibration) in the solvent bath of sump 2 for 30 seconds; 3. A solvent spray for 15 seconds;

solution is removed. This is sufficient for most purposes. Dipping the parts for about thirty seconds in an ultrasonically agitated bath of the same solvent, results in removal of the remaining 2 percent of the etching solution. The etching solution and the solvent are then separated in the separating zone after which the etching solution may be returned to process and the solvent returned for a subsequent drying operation.

1t will be obvious to anyone of ordinary skill in this art that modifications and variations may be made to the embodiments described herein. The essential elements of this invention consist of providing a vigorously agitated bath characterized by turbulence throughout the bath, or alternately, providing a solvent spray zone, transferring displaced liquid and solvent directly into a zone wherein solvent and liquid are permitted to separate into two phases, separating the phases and recycling solvent back to the treatment zone or to the separating zone. Choice of the solvent may also b critical, depending on the application.

As discussed above, a variety of additional treatment steps and structural components therefor may be incorporated with these essential elements and compounds of this invention, and the nature, number, or order of such additional treatment steps and necessary structural components therefor, do not represent a'departure from the scope and spirit of this invention.

lclaim:

1. The method for removing liquid from a non-absorbent article which comprises:

a. immersing an article containing a liquid contaminated surface into a solvent bath having a different density than the liquid and in which the liquid is between about 0.00 l-5 percent by weight soluble, which solvent bath is subjected to vigorous agitation to produce turbulence throughout the bath, thereby displacing liquid from the article,

b. transferring the displaced liquid and solvent directly to a separation zone, and

c. permitting the liquid and the solvent to separate into two phases therein,

d. withdrawing from the system liquid which collects as one phase in the separation zone,

e. removing from the separation zone solvent which collects as another phase in the separation zone,

f. recycling the solvent removed from the separation zone to the solvent bath, and

g. removing the article from the solvent bath.

2. The method according to claim 1 in which the solvent bath is maintained at a temperature below its boiling point and wherein the displaced liquid and solvent are transferred to the separation zone by overflow from the top of the solvent bath.

3. The method according to claim 2 in which the agitation in the solvent bath is produced by ultrasonic vibration.

4. The method according to claim 1 in which the agitation in the solvent bath is produced by vigorously agitating the article within the bath.

5. The method of claim 1 in which the article which is immersed into the solvent bath comprises a plurality of articles having surfaces in contact with one another, and in which the degree of turbulence produced throughout the bath is sufficient to cause such contactin g surfaces to separate from one another. 3

6. The method according to claim 2 in which the liquid is water.

7. The method according to claim 6 in which the solvent has a density greater than that of water and which therefore forms the lower phase in the separation zone.

8. The method according to claim 6 in which the solvent is one in which water is between about 0.01- percent by weight soluble.

9. The method according to claim 8 in which the agitation in the solvent bath is produced by ultrasonic vibration.

10. The method according to claim 8 in which the agitation in the solvent bath is produced by vigorously agitating the article within the bath.

1 1. The method according to claim 8 in which the article which is immersed into the solvent bath comprises a plurality of articles having surfaces in contact with one another, and in which the degree of turbulence produced throughout the bath is sufficient to cause such contacting surfaces to separate from one another.

12. The method according to claim 8 in which the article which is removed from the solvent bath is exposed to solvent vapors generated from a boiling solvent as defined herein in a second solvent bath.

13. The method according to claim 12 in which the second solvent bath is established with substantially water-free solvent liquid removed from the separation zone and inwhich the solvent vapors from the second solvent bath are condensed and cycled to the first solvent bath.

14. The method according to claim 8 in which the article is rinsed with a spray of a solvent as defined herein prior to immersion in the solvent bath.

15. The method according to claim 11 in which the solvent contains at least one substantially water-immiscible halogenated hydrocarbon component boiling between about 0-l00C. and having a density greater than about 1.3 gin/cm. at 20C. and at least one non halogenated organic liquid miscible with the halogenated hydrocarbon component and with water which boils between about 0-l 50C. and has a density less than about 1.0 gm./crn. at 20C.

16. The method according to claim 15 in which the solvent is a two component mixture in which the substantially water-immiscible component constitutes between about -.-99.5 weight percent of the mixture.

17. The method according to claim 16 in which the substantially water-immiscible component is a member of the group consisting of l.,l,2-trichloro-l,2,2- trifluoroethane and tetrachlorodifluoroethane and in which the water-miscible component is a member of the group consisting of methanol, ethanol, n-propanol, isopropanol, acetonitrile, acetone, nitromethane and dioxane.

18. The method according to claim 17 in which the agitation in the solvent bath is produced by ultrasonic vibration.

19. The method according to claim 18 in which the substantially water-immiscible component is 1,1,2- trichloro-l ,2,2-tritluoroethane and. in which the watermiscible component is isopropanol.

20. The method according to claim 18 in which the article which is removed from the solvent bath is exposed to solvent vapors generated from a boiling solvent as defined herein in a second solvent bath.

vent bath is established with substantially water-free solvent liquid removed from the separation zone and in which the solvent vapors from the second solvent bath are condensed and cycled to the first solvent bath.

22. The method according to claim 21 in which the substantially water-immiscible component is 1,1,2- trichloro-l,2,2-trifluoroethane and in which the watermiscible component is isopropanol.

23. The method according to claim 17 in which the agitation in the solvent bath is produced by vigorously agitating the article within the bath.

24. The method according to claim 23 in which the substantially water-immiscible component is 1,1,2- trichloro-l,2,2-trifluoroethane and in which the watermiscible component is isopropanol.

25. The method according to claim 24 in which the article which is removed from the'solvent bath is exposed to solvent vapors generated from a boiling solvent as defined herein in a second solvent bath.

2 6..The method according to claim 25 in which the second solvent bath is established with substantially water-free solvent liquid removed from the separation zone and in which the solvent vapors from the second solvent bath are condensed and cycled either to the first solvent bath or to the separation zone.

27. The method according to claim 26 in which the substantially water-immiscible component is 1,1,2- trichloro-l ,2,2-trifluoroethan e and in which the watermiscible component is isopropanol.

28. The method for removing liquid from a non-absorbent article which comprises:

a. spraying an article containing a liquid contaminated surface with a solvent having a different density than the liquid and in which the liquid is between about 0.001-5 percent by weight soluble, thereby displacing liquid from the article,

b. collecting the displaced liquid and solvent,

c. a second sump adapted to contain a liquid,

. means for transferring liquid which overflows from the first sump to the second sump,

e. means for removing liquid which collects as an upper phase from the upper portion of the second sump,

f. means for removing liquid which collects as a lower phase from the lower portion of the second sump, and

g. means for transferring liquid removed either from the lower portion of the second sump or from the upper portion of the second sump to the first sump.

60. Apparatus according to claim 44 which consists consists 

1. The method for removing liquid from a non-absorbent article which comprises: a. immersing an article containing a liquid contaminated surface into a solvent bath having a different density than the liquid and in which the liquid is between about 0.001-5 perceNt by weight soluble, which solvent bath is subjected to vigorous agitation to produce turbulence throughout the bath, thereby displacing liquid from the article, b. transferring the displaced liquid and solvent directly to a separation zone, and c. permitting the liquid and the solvent to separate into two phases therein, d. withdrawing from the system liquid which collects as one phase in the separation zone, e. removing from the separation zone solvent which collects as another phase in the separation zone, f. recycling the solvent removed from the separation zone to the solvent bath, and g. removing the article from the solvent bath.
 2. The method according to claim 1 in which the solvent bath is maintained at a temperature below its boiling point and wherein the displaced liquid and solvent are transferred to the separation zone by overflow from the top of the solvent bath.
 3. The method according to claim 2 in which the agitation in the solvent bath is produced by ultrasonic vibration.
 4. The method according to claim 1 in which the agitation in the solvent bath is produced by vigorously agitating the article within the bath.
 5. The method of claim 1 in which the article which is immersed into the solvent bath comprises a plurality of articles having surfaces in contact with one another, and in which the degree of turbulence produced throughout the bath is sufficient to cause such contacting surfaces to separate from one another.
 6. The method according to claim 2 in which the liquid is water.
 7. The method according to claim 6 in which the solvent has a density greater than that of water and which therefore forms the lower phase in the separation zone.
 8. The method according to claim 6 in which the solvent is one in which water is between about 0.01-5 percent by weight soluble.
 9. The method according to claim 8 in which the agitation in the solvent bath is produced by ultrasonic vibration.
 10. The method according to claim 8 in which the agitation in the solvent bath is produced by vigorously agitating the article within the bath.
 11. The method according to claim 8 in which the article which is immersed into the solvent bath comprises a plurality of articles having surfaces in contact with one another, and in which the degree of turbulence produced throughout the bath is sufficient to cause such contacting surfaces to separate from one another.
 12. The method according to claim 8 in which the article which is removed from the solvent bath is exposed to solvent vapors generated from a boiling solvent as defined herein in a second solvent bath.
 13. The method according to claim 12 in which the second solvent bath is established with substantially water-free solvent liquid removed from the separation zone and in which the solvent vapors from the second solvent bath are condensed and cycled to the first solvent bath.
 14. The method according to claim 8 in which the article is rinsed with a spray of a solvent as defined herein prior to immersion in the solvent bath.
 15. The method according to claim 11 in which the solvent contains at least one substantially water-immiscible halogenated hydrocarbon component boiling between about 0*-100*C. and having a density greater than about 1.3 gm./cm.3 at 20*C. and at least one non-halogenated organic liquid miscible with the halogenated hydrocarbon component and with water which boils between about 0*-150*C. and has a density less than about 1.0 gm./cm.3 at 20*C.
 16. The method according to claim 15 in which the solvent is a two component mixture in which the substantially water-immiscible component constitutes between about 80-99.5 weight percent of the mixture.
 17. The method according to claim 16 in which the substantially water-immiscible component is a member of the group consisting of 1,1,2-trichloro-1,2,2-trifluoroethane and tetrachlorodifluoroeThane and in which the water-miscible component is a member of the group consisting of methanol, ethanol, n-propanol, isopropanol, acetonitrile, acetone, nitromethane and dioxane.
 18. The method according to claim 17 in which the agitation in the solvent bath is produced by ultrasonic vibration.
 19. The method according to claim 18 in which the substantially water-immiscible component is 1,1,2-trichloro-1,2,2-trifluoroethane and in which the water-miscible component is isopropanol.
 20. The method according to claim 18 in which the article which is removed from the solvent bath is exposed to solvent vapors generated from a boiling solvent as defined herein in a second solvent bath.
 21. The method of claim 20 in which the second solvent bath is established with substantially water-free solvent liquid removed from the separation zone and in which the solvent vapors from the second solvent bath are condensed and cycled to the first solvent bath.
 22. The method according to claim 21 in which the substantially water-immiscible component is 1,1,2-trichloro-1,2,2-trifluoroethane and in which the water-miscible component is isopropanol.
 23. The method according to claim 17 in which the agitation in the solvent bath is produced by vigorously agitating the article within the bath.
 24. The method according to claim 23 in which the substantially water-immiscible component is 1,1,2-trichloro-1,2,2-trifluoroethane and in which the water-miscible component is isopropanol.
 25. The method according to claim 24 in which the article which is removed from the solvent bath is exposed to solvent vapors generated from a boiling solvent as defined herein in a second solvent bath.
 26. The method according to claim 25 in which the second solvent bath is established with substantially water-free solvent liquid removed from the separation zone and in which the solvent vapors from the second solvent bath are condensed and cycled either to the first solvent bath or to the separation zone.
 27. The method according to claim 26 in which the substantially water-immiscible component is 1,1,2-trichloro-1,2,2-trifluoroethane and in which the water-miscible component is isopropanol.
 28. The method for removing liquid from a non-absorbent article which comprises: a. spraying an article containing a liquid contaminated surface with a solvent having a different density than the liquid and in which the liquid is between about 0.001-5 percent by weight soluble, thereby displacing liquid from the article, b. collecting the displaced liquid and solvent, c. permitting the displaced liquid and the solvent to separate into two phases, d. causing the upper phase with accompanying amounts of the lower phase to overflow into a separation zone and permitting the liquid and the solvent to separate into two phases therein, e. withdrawing from the system liquid which collects as one phase in the separation zone, f. removing from the separation zone solvent which collects as another phase in the separation zone, g. recycling the solvent removed from the separation zone to the spray, and h. removing the article from the spray.
 29. The method according to claim 28 in which the solvent is sprayed at a temperature below its boiling point.
 30. The method according to claim 29 in which the liquid is water.
 31. The method according to claim 30 in which the solvent has a density greater than that of water and which forms therefore the lower phase in the separation zone.
 32. The method according to claim 30 in which the solvent is one in which water is between about 0.01-5 percent by weight soluble.
 33. The method according to claim 32 in which the article which is removed from the spray is exposed to solvent vapors generated from a boiling solvent bath, said solvent being as described herein.
 34. The method according to claim 33 in which the boiling solvent bath is supplied with substAntially water-free solvent liquid removed from the separation zone and in which the solvent vapors from the solvent bath are condensed and cycled to the solvent spray.
 35. The method according to claim 32 in which the solvent comprises a halogenated hydrocarbon boiling between about 0*-100*C. and having a density greater than about 1.3 gm./cm.3 at 20*C.
 36. The method according to claim 35 in which the solvent is a member selected from the group consisting of 1,1,2-trichloro-1,2, 2-trifluoroethane and tetrachlorodifluoroethane.
 37. The method according to claim 32 in which the solvent contains at least one substantially water-immiscible halogenated hydrocarbon component boiling between about 0*-100*C. and having a density greater than about 1.3 gm./cm.3 at 20*C. and at least one non-halogenated organic liquid miscible with the halogenated hydrocarbon component and with water which boils between about 0*-150*C. and has a density less than about 0.0 gm./cm.3 at 20*C.
 38. The method according to claim 8 which consists essentially of the steps described.
 39. The method according to claim 12 which consists essentially of the steps described.
 40. The method according to claim 14 which consists essentially of the steps described.
 41. The method according to claim 17 which consists essentially of the steps described.
 42. The method according to claim 32 which consists essentially of the steps described.
 43. The method according to claim 34 which consists essentially of the steps described.
 44. Apparatus which comprises in combination: a. a first sump adapted to contain a liquid, b. means to vigorously agitate liquid contained within the first sump and to produce turbulence throughout said liquid, c. a second sump adapted to contain a liquid, d. means for transferring liquid which overflows from the first sump to the second sump, e. means for removing liquid which collects as an upper phase from the upper portion of the second sump, f. means for removing liquid which collects as a lower phase from the lower portion of the second sump, and g. means for transferring liquid removed either from the lower portion of the second sump or from the upper portion of the second sump to the first sump.
 45. Apparatus according to claim 44 in which the first sump is free of heating means.
 46. Apparatus according to claim 45 in which the second sump is positioned adjacent the first sump so that liquid which overflows from the first sump flows directly into the second sump.
 47. Apparatus according to claim 45 in which the agitation means comprises a source of ultrasonic vibration.
 48. Apparatus according to claim 45 in which the agitation means comprises a means for agitating articles immersed in liquid contained within the first sump.
 49. Apparatus according to claim 45 which includes means for spraying articles with liquid.
 50. Apparatus according to claim 49 in which the spray means is located in proximity to the top of the first sump.
 51. Apparatus according to claim 44 which includes a third sump which is free of means to create turbulence in liquid contained within said sump.
 52. Apparatus according to claim 51 which is provided with means for transferring liquid which overflows from the third sump to the second sump.
 53. Apparatus according to claim 44 which includes: a. a boiling sump, including heating means, b. means for transferring liquid either from the lower portion the second sump or from the upper portion of the second sump to the boiling sump, c. means for condensing vapor generated in the boiling sump, d. means for cycling the condensate to the de-watering sump.
 54. Apparatus according to claim 53 in which the first sump is free of heating means.
 55. Apparatus according to claim 54 in which the second sump is positioned adjacent the first sump so that liquid which overflows from the first sump flows directly into the second sump.
 56. Apparatus according to claim 54 in which the agitation means comprises a source of ultrasonic vibration.
 57. Apparatus according to claim 54 in which the agitation means comprises a means for agitating articles immersed in liquid contained within the first sump.
 58. Apparatus according to claim 54 which includes means for spraying articles with liquid.
 59. Apparatus which comprises in combination: a. means to spray articles with liquid, b. a first sump adapted to receive liquid which is discharged from the spray means, c. a second sump adapted to contain a liquid, d. means for transferring liquid which overflows from the first sump to the second sump, e. means for removing liquid which collects as an upper phase from the upper portion of the second sump, f. means for removing liquid which collects as a lower phase from the lower portion of the second sump, and g. means for transferring liquid removed either from the lower portion of the second sump or from the upper portion of the second sump to the first sump.
 60. Apparatus according to claim 44 which consists essentially of the components recited.
 61. Apparatus according to claim 47 which consists essentially of the components recited.
 62. Apparatus according to claim 48 which consists essentially of the components recited.
 63. Apparatus according to claim 49 which consists essentially of the components recited.
 64. Apparatus according to claim 53 which consists essentially of the components recited.
 65. Apparatus according to claim 56 which consists essentially of the components recited.
 66. Apparatus according to claim 59 which consists essentially of the components recited. 